Date: Wed, 11 Sep 2013 13:08:32 +0000 From: "Eggert, Lars" <lars@netapp.com> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: "<stable@freebsd.org>" <stable@freebsd.org> Subject: Re: nfsd CPU usage? Message-ID: <A24A8E32-53AA-45F1-ADDA-2C55863018B5@netapp.com> In-Reply-To: <995078453.21651811.1378900450650.JavaMail.root@uoguelph.ca> References: <995078453.21651811.1378900450650.JavaMail.root@uoguelph.ca>
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Thanks, I will watch out for the MFC and test.
Lars
On Sep 11, 2013, at 13:54, Rick Macklem <rmacklem@uoguelph.ca> wrote:
> Lars Eggert wrote:
>> Hi,
>>=20
>> I'm seeing extremely high CPU usage withssh-st the new nfsd:
>>=20
>> PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU
>> COMMAND
>> 2280 root 102 0 9932K 1376K *nfs_c 0 320:11 100.00%
>> nfsd{nfsd: service}
>> 2280 root 102 0 9932K 1376K CPU7 7 319:47 100.00%
>> nfsd{nfsd: service}
>> 2280 root 102 0 9932K 1376K CPU5 5 318:25 100.00%
>> nfsd{nfsd: service}
>> 2280 root 102 0 9932K 1376K CPU6 6 318:20 100.00%
>> nfsd{nfsd: service}
>> 2280 root 52 0 9932K 1376K CPU0 0 317:32 100.00%
>> nfsd{nfsd: service}
>> 2280 root 102 0 9932K 1376K *nfs_c 1 315:41 99.17%
>> nfsd{nfsd: service}
>> 2280 root 52 0 9932K 1376K *nfs_c 4 320:22 98.78%
>> nfsd{nfsd: master}
>> 2280 root 102 0 9932K 1376K *nfs_c 1 317:10 98.10%
>> nfsd{nfsd: service}
>>=20
>> And this is at a few hundred KB/s with only a few clients:
>>=20
>> ifstat -i igb1 10
>> igb1
>> KB/s in KB/s out
>> 796.56 208.66
>> 431.19 232.36
>> 316.11 280.31
>> 1005.96 523.42
>> 1077.74 342.25
>> 340.63 217.73
>> 1067.96 330.56
>> 487.91 235.61
>>=20
>> Any ideas?
>>=20
>> FreeBSD stanley.muccbc.hq.netapp.com 9.2-PRERELEASE FreeBSD
>> 9.2-PRERELEASE #7: Wed Sep 4 11:06:31 CEST 2013
>> root@stanley.muccbc.hq.netapp.com:/usr/obj/usr/src/sys/STANLEY
>> amd64
>>=20
>> Thanks,
>> Lars
>>=20
> There is a patch in head (r254337) that I believe handles this.
> It will be MFC'd to stable/9 in about a week, unless someone finds
> problems with it before then.
> If you want a semantically equivalent (but uglier code) patch,
> you can find it here:
> http://people.freebsd.org/~rmacklem/drc4-stable9.patch
> After applying the patch, you need to set sysctl variable(s),
> to avoid the aggressive trimming of stale DRC entries. Garrett
> Wollman suggests the following for a large server:
> vfs.nfsd.tcphighwater=3D100000
> vfs.nfsd.tcpcachetimeout=3D300 (5 minutes instead of default of =
several hrs)
>=20
> You can also use the sysctl
> vfs.nfsd.cachetcp=3D0
> to disable use of the DRC for TCP.
>=20
> The old nfs server did not use the DRC for TCP. The assumption being =
that
> TCP layer retransmits are good enough to maintain reliable RPC =
transport.
> Unfortuantely, you can get file corruption when the server reboots or
> there is a network partitioning, if the client chooses to redo the RPC
> over TCP (clients always do this after having to create a new TCP =
connection).
> In other words, vfs.nfsd.cachetcp=3D0 is roughly what the old nfsd =
did.
>=20
> If you don't want to patch the 9.2 code, you can edit the sources
> (sys/fs/nfsserver/nfs_nfsdcache.c) and change the line:
> static int nfsrc_tcpnonidempotent =3D 1;
> to
> static int nfsrc_tcpnonidempotent =3D 0;
> to do the same thing as vfs.nfsd.cachetcp=3D0
>=20
> rick
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